Viral encephalitis

Question 1

What is encepahlitis

Answer 1

Inflammation of brain parenchyma

Question 2

What viruses most commonly cause encephalitis

Answer 2

HSV - 20%
VZV - 5%

Question 3

Causes of viral encepahlitis

Answer 3

Imported eg Japanese B enceph.
other infections eg TB
Acute disseminated encephalomyelitis - ADEM (infection or vaccination trigger)
Antibody mediated encephalitis eg anti-NMDA, anti-VGK+C antibodies

Question 4

Classical sympotms of encephalitis

Answer 4

Fever
Headache
Reduced consciousness level
Personality or behaviour change
New onset of seizures
Diagnosis often delayed

Question 5

In a patient with fever and headache what is viral encephalitis suggested by

Answer 5

Seizures
Focal neurological signs
Neuropsychiatric features - confusion, personality change, agitation, hallucinations
Perform full neuro exam

Question 6

Why is GCS not that helpful for diagnosing encephalitis

Answer 6

Crude/late sign of confusion
Early collateral history will pick up on subtle signs earlier

Question 7

General findings in viral encephalitis on LP

Answer 7

Increased lymphocytes
Increased protein
Normal glucse

Question 8

Tests for viral encephalitis

Answer 8

LP
Specific tests
PCR on CSF - HSV, VZV and enteroviruses
Clinical features differentiate from viral meningitis

Question 9

What further tests do if diagnosis of viral encephalitis unclear

Answer 9

Neuro-imaging - MRI
EEG
HIV test
If travel historu serology and PCR for neurotropic viruses

Question 10

What does EEG exclude in viral encephalitis

Answer 10

subtle motor seizures or non convulsive status epilepticus

Question 11

Can exclude HSV-1 encephalitis if negative LP?

Answer 11

No - 10% have initial negative LP

Question 12

What do if negative LP for HSV-1 encephalitis but still clinical suspicion

Answer 12

Repeat LP in 24-48 hours

Question 13

When can HSV-1 encephalitis be excluded

Answer 13

HSV PCR negative on 2 occasions 24-48 hours apart, MRI normal
HSV CR negative ONCE >72 hrs after neuro symptom onset, unaltered consciousness, normal MRI, CSF WCC <5 cells/mm3

Question 14

Treatment for viral encephalitis

Answer 14

General support - supervise, reassure, fluid and hydration, feeding, treat complications eg seizures
Anti-viral therapy if clinical suspicion

Question 15

What is anti-viral treatment for HSV-1 encephalitis

Answer 15

IV aciclovir 10mg/kg 3 x daily
14-21 day course required

Question 16

Prognosis of HSV-1 encephalitis

Answer 16

no treatmnet - 70% die
treatment - 10-20% die
Worse outcomes delay treatment >24 hours

Question 17

Acute complications of HSV encephalitis

Answer 17

Venous sinus thrombosis
Status epilepticus
Stroke
Aspiration pneumonia

Question 18

Long term morbidity of HSV-1 encephalitis

Answer 18

60% of surviors left with permanent neurological disability
Specialist neuro-rehab required

Question 19

What should do immediately if clinical suspicion of viral encephalitis

Answer 19

IV aciclovir immediately